The 3D ocean map that could reveal exactly what effect global warming is having on rainfall
Nasa is planning to create a 3D map of the ocean that could reveal exactly what effect global warming is having on rainfall.
The expedition is set to sail to the North Atlantic's saltiest spot to get a detailed, 3D picture of how salt content fluctuates in the ocean's upper layers and how these variations are related to shifts in rainfall patterns around the planet.
The research voyage is part of a multi-year mission, dubbed the Salinity Processes in the Upper Ocean Regional Study (SPURS), which will deploy multiple instruments in different regions of the ocean.
Nasa's mission will study salt levels in the north Atlantic and create the first 3D map of salt levels as they flow around the ocean
The new data also will help calibrate the salinity measurements NASA's Aquarius instrument has been collecting from space since August 2011.
Scientists above the vessel Neurr are already heading for a spot known as the Atlantic surface salinity maximum, located halfway between the Bahamas and the western coast of North Africa.
The researchers will spend about three weeks on site deploying instruments and taking salinity, temperature and other measurements.
They aim to return with new data to aid in understanding one biggest effects of climate change, the acceleration of Earth's water cycle.
As global temperatures go up, evaporation increases, altering the frequency, strength, and distribution of rainfall around the planet, with far-reaching implications for life on Earth.
How it will work: Nasa plans to employ a variety of sensors and underwater floats to collect data for the project
'What if the drought in the U.S. Midwest became permanent? To understand whether that could happen we must understand the water cycle and how it will change as the climate continues to warm's said Raymond Schmitt, a physical oceanographer at Woods Hole and principal investigator for SPURS.
'Getting that right is going to involve understanding the ocean, because the ocean is the source of most of the water.'
Oceanographers believe the ocean retains a better record of changes in precipitation than land, and translates these changes into variations in the salt concentration of its surface waters.
Scientists studying the salinity records of the past 50 years say they already see the footprint of an increase in the speed of the water cycle.
The places in the ocean where evaporation has increased and rain has become scarcer have turned saltier over time, while the spots that now receive more rain have become fresher.
This acceleration may exacerbate droughts and floods around the planet, researchers believe.
Some climate models, however, predict less dramatic changes in the global water cycle, and researchers hope to find out what is really occuring.
'With Spurs we hope to find out why these climate models do not track our observations of changing salinities," said Eric Lindstrom, physical oceanography program scientist at Nasa.
'We will investigate to what extent the observed salinity trends are a signature of a change in evaporation and precipitation over the ocean versus the ocean's own processes, such as the mixing of salty surface waters with deeper and fresher waters or the sideways transport of salt.'
Current maps of salinity levels are not as accurate as the new 3D version
Researchers will deploy an array of instruments and platforms, including autonomous gliders, sensor-laden buoys and unmanned underwater vehicles.
Some will be collected before the research vessel heads to the Azores, but others will remain in place for a year or more, providing scientists with data on seasonal variations of salinity.
The Knorr research vessel will deploy a range of sensors to create a 3D map of ocean's saltiest area.
'We'll be able to look at lots of different scales of salinity variability in the ocean, some of which can be seen from space, from a sensor like Aquarius,' said David Fratantoni, a physical oceanographer with Woods Hole and a member of the expedition.
'But we're also trying to see variations in the ocean that can't be resolved by current satellite technology.'
A second expedition in 2015 will investigate low-salinity regions where there is a high input of fresh water, such as the mouth of a large river or the rainy belts near the equator.